Archive for October, 2010

The EPA has proposed new rules directed at emissions from sewage sludge incinerator (SSI) units. SSI units are typically found at wastewater treatment facilities and, according to the EPA, are the sixth-largest source of mercury air emissions in the US. The proposal not only limits mercury emissions, but also sets standard and emission guidelines for eight other pollutants, including lead, cadmium, hydrogen chloride, particulate matter, carbon monoxide, dioxins and furans, nitrogen oxide, and sulfur dioxide. However, mercury is of particular interest because the proposed emission standard is more stringent than the mandates that were set under the Clean Air Act.

Recently, the EPA announced it intends to propose a rule to reduce mercury waste from dental offices. Mercury is a concern to human health because it is considered a persistent bioaccumulative toxic element.

According to the EPA, dental amalgams, or fillings containing mercury, account for 3.7 tons of mercury discharged into US waterways each year.

The EPA is considering hexabromocyclododecane, a brominated flame retardant made up of various mixtures of its 16 isomers (herein: HBCD), for action under the Toxic Substance Control Act (TSCA). This is in addition to two other groups of compounds already discussed in previous Lab Science News articles.

HBCD is ubiquitous in the environment throughout the world and is also found in human tissues, including blood, adipose, and breast milk. When released into the environment, it can travel great distances, bioaccumulating and biomagnifing in the food chain. In addition to its high toxicity to aquatic organisms, studies have also linked HBCD to reproductive, developmental, and neurological effects in humans, with a potentially higher impact on children because of their smaller size.

This article discusses the EPA’s action plans for the compounds, nonylphenol (NP) and nonylphenol ethoxylates (NPEs).

The EPA released new action plans on August 18th, 2010 to review the potential health risks of Benzidene and its congeners, Nonylphenol (NP) and Nonylphenol Ethoxylates (NPEs), and Hexabromocyclododecane (HBCD). These compounds were chosen based on their presence in humans, their persistent, bioaccumulative, and toxic (PBT) characteristics, and their use in consumer products and production.1 The action plans may result in new use rules, new reporting limits, or the banning or limiting their production and use.

According to the EPA’s Action Plan, a major reason for reviewing NP and NPEs is their widespread release into, and their toxicity in, the aquatic environment. NP is actually a mixture of various structured compounds, that differ in their level of toxicity. NP is used primarily in manufacturing NPEs, which first break down into shorter chain NPEs over time, and then eventually back to NP. While NP is more toxic than the NPEs, they are all toxic to plants, fish and aquatic invertebrates.